package com.togo.algorithm.easy.design;

import java.util.LinkedList;

/**
 * @Author taiyn
 * @Description
 * 用两个栈实现一个队列。队列的声明如下，请实现它的两个函数 appendTail 和 deleteHead ，分别完成在队列尾部插入整数和在队列头部删除整数的功能。(若队列中没有元素，deleteHead 操作返回 -1 )
 *
 *  
 *
 * 示例 1：
 *
 * 输入：
 * ["CQueue","appendTail","deleteHead","deleteHead","deleteHead"]
 * [[],[3],[],[],[]]
 * 输出：[null,null,3,-1,-1]
 * 示例 2：
 *
 * 输入：
 * ["CQueue","deleteHead","appendTail","appendTail","deleteHead","deleteHead"]
 * [[],[],[5],[2],[],[]]
 * 输出：[null,-1,null,null,5,2]
 * 提示：
 *
 * 1 <= values <= 10000
 * 最多会对 appendTail、deleteHead 进行 10000 次调用
 *
 * @Date 2:30 PM 2023/5/24
 **/
public class Offer09 {

    LinkedList<Integer> l1;
    LinkedList<Integer> l2;

    public Offer09() {
        l1 = new LinkedList<>();
        l2 = new LinkedList<>();
    }

    public void appendTail(int value) {
        l1.addLast(value);
    }

    public int deleteHead() {
        if(l2.size() > 0) return l2.removeLast();
        if(l1.size() == 0) return -1;

        while (l1.size() > 0) {
            l2.addLast(l1.removeLast());
        }

        return l2.removeLast();
    }
}
